Originally posted by: SystemAdmin

Hello :)

I have a complex objective function where the final expression is created by aggregating snippet expressions in the model. That is, lets assume following simplified objective function:
F = e1 + e2 +...en where

IloLinearNumExpr e1,e2,e3
e1.addTerm(5, X[0]);
e1.addTerm(3, X[1]);
e1.addTerm(7, X[2]);
e1.setConstant(10);

e2.addTerm(10, X[6]);
....
e2.addTerm(n, X[9]);

IloNumExpr e3 = model.min(e1,e2);
...
...
en
What is really needed to build up the final expression is casting IloNumExpr expressions (e.g., e3) to IloLinearNumExpr in the course of iteration to be able to create the final expression in a loop. However, the casting is not plausible. So I'm wondering how we can deal with
Some parts of the objective function expression include min/max. I'm wondering if anybody can shed some lights for expression aggregation since there is no way for casting
I'm grateful for some help on this topic.
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Originally posted by: SystemAdmin

Not sure if I understood correctly what you want to do. Can you just use operator+=?

IloNumExpr e1 = x + y;
IloNumExpr e2 = x - y;
IloNumExpr agg(env);
agg += e1;
agg += e2;

This allows you to add up instances of IloNumExpr.
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Originally posted by: SystemAdmin

Many thanks Daniel. I already solved it by following up Rubin's suggestion as well
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Originally posted by: SystemAdmin

Following up on Daniel's response, if you're using the Java API, you can nest zillions of model.sum() and model.prod() calls to combine IloNumExprs.

Paul

Mathematicians are like Frenchmen: whenever you say something to them, they translate it into their own language, and at once it is something entirely different. (Goethe)
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Originally posted by: SystemAdmin

Thanks a lot Paul :) It was helpful. Actually I was about thinking to cast IloNumExpr expressions to IloLinearNumExpr ones rather than generating in that way.
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